Gradebook

I would like to have a section for teacher comments in the gradebook, where teachers can add free text.

I know that feedback can be added to any graded item, and the feedback can be viewed by the teacher by hovering over the grade, but I would like a separate column with text visible, so that the teacher can see the comments for all students at once.

I tried adding an offline assignment and setting the grade to No value, but when I added text to the feedback, this was not visible to a non-editing teacher (even when hovering over the space).

I also tried adding a Grade item, with text only - again, I could add text, but this was not then visible to the teacher.

In both cases the comment appears in the student user report, but this deesn't help the teacher who wants to look at the whole class.

Can this be done? (I am using Moodle 1.9.3+).

Thanks.